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            <small>
              <a href="#Procedure">Procedure<br></a>
              <a href="#Abstract">Abstract<br></a>
              <a href="#Required_Reading">Required_Reading<br></a>
              <a href="#Keywords">Keywords<br></a>
              <a href="#Brief_I/O">Brief_I/O<br></a>
              <a href="#Detailed_Input">Detailed_Input<br></a>

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              <small>               <a href="#Detailed_Output">Detailed_Output<br></a>
              <a href="#Parameters">Parameters<br></a>
              <a href="#Exceptions">Exceptions<br></a>
              <a href="#Files">Files<br></a>
              <a href="#Particulars">Particulars<br></a>
              <a href="#Examples">Examples<br></a>

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              <small>               <a href="#Restrictions">Restrictions<br></a>
              <a href="#Literature_References">Literature_References<br></a>
              <a href="#Author_and_Institution">Author_and_Institution<br></a>
              <a href="#Version">Version<br></a>
              <a href="#Index_Entries">Index_Entries<br></a>
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<h4><a name="Procedure">Procedure</a></h4>
<PRE>
   SpiceBoolean vzero_c ( ConstSpiceDouble v[3] ) 

</PRE>
<h4><a name="Abstract">Abstract</a></h4>
<PRE>
 
   Indicate whether a 3-vector is the zero vector. 
 </PRE>
<h4><a name="Required_Reading">Required_Reading</a></h4>
<PRE>
 
   None. 
 </PRE>
<h4><a name="Keywords">Keywords</a></h4>
<PRE>
 
   MATH 
   VECTOR 
 

</PRE>
<h4><a name="Brief_I/O">Brief_I/O</a></h4>
<PRE>
 
   Variable  I/O  Description 
   --------  ---  -------------------------------------------------- 
   v          I   Vector to be tested. 
 
   The function returns the value SPICETRUE if and only if v is the 
   zero vector. 
 </PRE>
<h4><a name="Detailed_Input">Detailed_Input</a></h4>
<PRE>
 
   v          is a vector in 3-space. 
 </PRE>
<h4><a name="Detailed_Output">Detailed_Output</a></h4>
<PRE>
 
   The function returns the value SPICETRUE if and only if v is the 
   zero vector. 
 </PRE>
<h4><a name="Parameters">Parameters</a></h4>
<PRE>
 
   None. 
 </PRE>
<h4><a name="Exceptions">Exceptions</a></h4>
<PRE>
 
   Error free. 
 </PRE>
<h4><a name="Files">Files</a></h4>
<PRE>
 
   None. 
 </PRE>
<h4><a name="Particulars">Particulars</a></h4>
<PRE>
 
   This function has the same truth value as the logical expression 
 
      <a href="vnorm_c.html">vnorm_c</a> ( v )  ==  0. 
 
   Replacing the above expression by 
 
      <b>vzero_c</b> ( v );
 
   has several advantages:  the latter expresses the test more 
   clearly, looks better, and doesn't go through the work of scaling, 
   squaring, taking a square root, and re-scaling (all of which 
   <a href="vnorm_c.html">vnorm_c</a> must do) just to find out that a vector is non-zero. 
 
   A related function is vzerog_, which accepts vectors of arbitrary 
   dimension. 
 </PRE>
<h4><a name="Examples">Examples</a></h4>
<PRE>
 
   1)  When testing whether a vector is the zero vector, one 
       normally constructs tests like 
 
          if (  <a href="vnorm_c.html">vnorm_c</a> ( v ) ==  0.  )
             { 
                      . 
                      . 
                      . 
 
 
       These can be replaced with the code 
 
          if (  <b>vzero_c</b> ( v )  ) 
             {
                      . 
                      . 
                      . 
 
 
    2)  Check that a normal vector is non-zero before creating 
       a plane with PNV2PL: 
 
       if (  <b>vzero_c</b> ( NORMAL )  )
          {
          [ handle error ] 
          }
 
       else
          { 
          pnv2pl_ ( POINT, NORMAL, PLANE ) 
                        . 
                        . 
                        . 
          }
</PRE>
<h4><a name="Restrictions">Restrictions</a></h4>
<PRE>
 
   None. 
 </PRE>
<h4><a name="Literature_References">Literature_References</a></h4>
<PRE>
 
   None. 
 </PRE>
<h4><a name="Author_and_Institution">Author_and_Institution</a></h4>
<PRE>
 
   N.J. Bachman   (JPL) 
   I.M. Underwood (JPL) 
 </PRE>
<h4><a name="Version">Version</a></h4>
<PRE>
 
   -CSPICE Version 1.1.0, 22-OCT-1998 (NJB)

      Made input vector const.  Removed #include of SpiceZfc.h.

   -CSPICE Version 1.0.0, 08-FEB-1998 (EDW)
</PRE>
<h4><a name="Index_Entries">Index_Entries</a></h4>
<PRE>
 
   test whether a 3-dimensional vector is the zero vector 
 </PRE>
<h4>Link to routine vzero_c source file <a href='../../../src/cspice/vzero_c.c'>vzero_c.c</a> </h4>

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   <pre>Wed Jun  9 13:05:33 2010</pre>

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